1. Field of the Invention
The present invention relates to a battery system, especially a battery system which allows either batteries with same specifications in series for batteries' status easily monitored or series-parallel batteries for any battery freely replaced during maintenance and significantly reduced cost in design or maintenance.
2. Description of the Prior Art
The digital interface frequently observed in batteries of a common electric car is used to control charge/discharge of the electric car's power system and to monitor batteries' residual capacity and working status. During development of an electric vehicle's power system, the series-parallel batteries have become a consequential tendency on the basis of a battery's gradually increased capacity or power and consideration of the best capacity-combination. And the replacement and maintenance of the batteries for a digital monitoring system must be taken into account. In the previous patents for digital interfaces with respect to battery management, most digital integrated interfaces are categorized to the One-Wire Bus, Maxim/HDQ Bus, Ti/the Smart Management Bus, Intel/CAN-Bus, Controller Area Network. Those kinds of communication interface are free from master-slave configuration issues, but there is no consideration of potential voltage. Therefore, the digital signal transmitted in those digital interface shall be with the same voltage-level, or sequentially voltage-level shifting. As consideration the flexibility of modular design, we need a new digital interface free from the potential-voltage problem and allowing the power cable of the battery modules connected in serial or parallel as power system needed.